This invention relates to a weighing dish made of paper, and a method in which a dry chemical or other dry laboratory material is held in that dish during weighing, and then quantitatively transferred to a receiving container. The weighing dish is fabricated from a lightweight high lubricity paper that allows quantitative transfer of the material after weighing, in which the dish has at least a bottom wall and a surrounding perimeter sidewall that includes pleats or flutes, and is continuous with the bottom wall.
Disposable weighing dish containers have been used for many years to hold materials such as granular chemicals and powders that are being weighed on preparative and analytical balances. Weighing dishes fabricated from plastic or aluminum foil are generally preferred over beakers and flasks for receiving and weighing out chemicals because they are lightweight (allowing use on low weight capacity precision balances) and are shallow, i.e., they have short sidewalls. Therefore, weighing dishes allow convenient and direct access for adding or removing material during weighing. Weighing dishes are generally manufactured under conditions that allow them to remain free of any contaminants. However, there are at least two drawbacks to the use of plastics and metal foils for the fabrication of weighing dishes. These include the build-up of static electricity, and the consequent static cling problem with fine powders that are weighed in plastic dishes, and the problem of particles of material being trapped in the creases typically found in shaped metal foil dishes.
Applicant is unaware of any prior art either in the patent literature, in scientific equipment catalogs or elsewhere relating to the presently invented paper weighing dish. A variety of die-cut and formed paper plates and bowls as well as cut and lap-joined paper trays are available in the food service industry, but most of these containers are either fabricated from unsuitable materials or unsuitably configured for use in the present invention. Applicant finds no suggestion in the literature that pleated paper structures can be adapted for use as disposable weighing dishes in the laboratory. On the worldwide web, numerous sites provide information on plastic and aluminum weighing dishes, but none suggest the existence of paper weighing dishes.